1. Field of the Invention
The present invention relates to clamps used to hold work pieces which are to be joined. Specifically, the invention relates to spring clamps having clamping components acting in a single plane along two axes for use in affixing edge pieces to surface pieces such as table and counter tops.
2. Description of the Prior Art
In various industries, but particularly in the laminate industry and in solid surface industries using Corian, Fountainhead, Gibraltar, and Avonite, there has long been a need for clamps to hold edge pieces to be joined to surface pieces for use in fabricating counter tops, tables, and other products. For example, it is often necessary to adhere an edge strip or facing to a counter top or table. Dual-action or compound clamps are useful for holding such pieces, and many dual-action clamps have been developed specifically for such use. Such clamps generally have a first clamping component which clamps in one axis in a plane defined by the clamping component, and a second clamping component which clamps in the same plane but on a different axis from the first clamping component. In use, the first clamping component holds the clamp securely to the surface work piece while the second clamping component, usually acting in an axis perpendicular to the first clamping component, holds the edge piece against the side of the surface work piece.
Examples of such clamps are disclosed in U.S. Pat. No. 242,959 Naglee, and in U.S. Pat. No. 1,402,621 Knittel and Kesslering. However, certain problems are inherent in the clamps disclosed in the above patents. The first clamping component of each of these clamps includes two opposed coaxial clamping screws which provide a force for clamping in a first clamping axis. The second clamping component also includes a clamping screw. Application of the clamp to the work requires adjustment of all three clamping screws. Turning each clamping screw is a relatively slow process. Slow application of clamps to the working pieces is a particular problem in fabricating counter tops because long edge strips typically require many clamps to secure the edge strips until the adhesive sets. Typically, the adhesives used to bond the edge strips become tacky very rapidly, preventing realignment after a short time. Therefore, the time required to place and adjust each clamp is critical.
Other solutions, have been proposed to solve this problem with limited success. For example, the clamp disclosed in, U.S. Pat. No. 2,624,905, Hewat, uses only two clamping screws instead of three. However, in Hewat the clamping screw of the second clamping component is mounted to the side of the frame. This configuration results in clamping force being directed along a clamping axis which is beside the frame and out of a plane defined by the first clamping component. This causes torque about the frame which can cause the entire clamp to twist. Once the clamp twists, the second clamping component is directed at an angle to the work pieces. The twisting of the clamps is a particular problem because when the clamp twists, the edge piece will tend to slide on the adhesive. Any such sliding of the work pieces may cause disastrous results as the edge piece may become permanently adhered to the work piece in an incorrect position. The clamp U.S. Pat. No. 1,788,546 in Schmieder, suffers from the same problem due to its similar configuration.
The clamp disclosed in U.S. Pat. No. 4,957,257, Gonzalez, attempts to overcome both the problem of time consuming adjustment, and of twisting caused by a second clamping component acting outside the plane of the first clamping component. The speed at which the Gonzalez clamp may be applied is increased by allowing one arm of the first clamping component to slide into contact with the work piece before adjusting the threaded clamping component in the first clamping plane. Twisting is avoided by having the second clamping component act within the same plane as the first clamping component. However, installation and adjustment is still accomplished with threaded clamping components which must each be adjusted in a time consuming process in each clamping axis.
There are several other problems with the prior art dual-action clamps which have not been addressed. For example, the pressure exerted by the clamps must be constant even as the pieces may be drawn closer together as the adhesive dries. The pressure exerted by the threaded clamping components of the prior art clamps does not automatically adjust, and time consuming manual re-adjustment of the threaded clamping components may be necessary. Additionally, it is difficult to gage the pressure being exerted by the threaded clamping components of the prior art clamps. Consequently it is easy to exceed the maximum recommended clamping pressure for the materials on which the clamp is used, or to apply too little pressure, possibly causing damage to the materials or negatively effecting the appearance of the materials. For example, too much pressure may mar the surfaces of the material to which the clamps are applied, or may squeeze too much adhesive out of the joint between the work pieces, thereby weakening the joint. Too little pressure may leave a conspicuous glue line.
The present invention provides a solution to each of the problems discussed above, by providing a quick and easy to use clamp with clamping components acting within a single plane, having a spring force which is calibrated not to exceed the recommended clamping pressure for the materials on which the clamp is used, and which automatically adjust to provide a constant pressure even as the work pieces are drawn closer together as the adhesive dries.